A single bad arrow tells you very little. A repeated pattern across several ends is useful. First decide whether you have a consistent group in the wrong place or a group that is spreading in several directions.
Consistent group, wrong place
If the group is tight, check your sight mark and windage before changing technique. A good group can normally be moved.
High and low patterns
Check anchor height, head position, bow shoulder, draw length and whether you are creeping forward before release. Also confirm the sight has not moved.
Left and right patterns
Check string alignment, release, bow-hand torque and consistent anchor. For tuned recurve equipment, button and centre-shot settings may matter, but technique should be checked first.
Change one thing
Do not move the sight, button, brace height and technique simultaneously. Make one sensible change, shoot enough arrows to judge it, and record the result.
Further reading and club guidance
Use this guide alongside coaching, the club risk assessment and the current rules for the round or event you are shooting. Safety instructions from the field captain, coach or judge always take priority.